1. Technical Filed
The present invention relates to a lighting apparatus, which is the most suitable for use mainly in a studio such as a TV studio.
2. Description of Related Art
Conventional lighting apparatuses used in a studio such as a TV studio employ a halogen lamp or a xenon lamp called HID. The halogen lamp has a feature that a color temperature can be high in high efficiency as a filament heating type light source. Particularly, the halogen lamp has a feature that can vary the color temperature by controlling voltage or current so as to adjust a filament temperature. However, the halogen lamp has a disadvantage that its lifetime is short. In particular, if the filament temperature is high so as to achieve a high color temperature, its lifetime tends to be sharply shortened. On the other hand, the xenon lamp has the feature that its lifetime can be long even if its color temperature is higher than in the case of the halogen lamp. But, since the xenon lamp cannot adjust the intensity of its light emission or its color temperature extensively, it has the disadvantage that the intensity of the light emission and the color temperature are constant.
Besides, neither the halogen lamp nor the xenon lamp can quickly vary the intensity of their light emission. Since the halogen lamp changes the light emission or the color of light emission by varying the filament temperature, there is a considerable delay in adjustment. The xenon lamp has another disadvantage in that it takes a considerable period of time for restarting of the xenon lamp after turned off. Accordingly, the halogen lamp and the xenon lamp have a disadvantage that they cannot be used in the case of the applications where it is necessary to quickly change intensity of light emission or color of light emission.
Therefore, the present invention has been developed to solve the above disadvantages. It is an important object of the present invention to provide a lighting apparatus capable of varying both a color temperature and an intensity of light emission extensively.
It is another significant object of the present invention to provide a lighting apparatus capable of varying both a color temperature and an intensity of light emission very quickly.
It is another significant object of the present invention to provide a lighting apparatus capable of maintaining a chromaticity coordinates (color temperature) specified once.
It is another significant object of the present invention to provide a lighting apparatus capable of focusing the illumination range to a very narrow spot or of scattering the light radiation over a wide range.
It is still another significant object of the present invention is to provide a lighting apparatus with a long lifetime and capable of achieving simple maintenance and control.